The invention pertains to methods of transferring patterns from photoresists to materials, and also pertains to structures comprising silicon nitride.
A commonly utilized process for patterning structures utilized for integrated circuitry is photolithographic processing. An imagable material (typically photoresist) is provided over a mass which is ultimately to be patterned. Portions of the imagable material are then exposed to radiation, while other portions remain unexposed (in the case of photoresist, the radiation is light). After the exposure, the material is subjected to conditions which selectively remove either the portions of the exposed to radiation, or the portions which were not exposed to radiation. If the imagable material comprises photoresist and the portions exposed to radiation are removed, the photoresist is referred to as a positive photoresist, whereas if the portions which are not exposed to radiation are removed the photoresist is referred to as a negative photoresist. Once the imagable material is patterned, it is utilized as a masking layer for patterning the underlying mass. Specifically, the patterned imagable material covers some portions of the mass, while leaving other portions exposed to an etch which removes the exposed portions. Accordingly, the mass remaining after the etch is in approximately the same pattern as the patterned imagable material formed over the mass.
Photolithographic processing is utilized for patterning numerous materials, including silicon nitride. However, problems can occur during the utilization of photolithographic processing for patterning silicon nitride. Specifically, the pattern formed in silicon nitride is frequently not the same as the pattern which was intended to be formed in the photoresist. Such problem can be particularly severe when utilizing photoresist patterned with deep UV light processing, wherein deep UV light is defined as ultraviolet light having a wavelength of less than or equal to 248 nanometers. It would be desirable to develop methods for avoiding the above-discussed problems.
In one aspect, the invention includes a semiconductor processing method. A first material comprising silicon and nitrogen is formed. A second material is formed over the first material, and the second material comprises silicon and less nitrogen (by atom percent) than the first material. An imagable material is formed on the second material, and patterned. A pattern is then transferred from the patterned imagable material to the first and second materials.
In another aspect, the invention encompasses a method of forming a patterned structure. A first layer comprising silicon and nitrogen is formed over a substrate. A sacrificial layer is formed on the first layer, and comprises less nitrogen (by atom percent) than the first layer. A layer of imagable material is formed on the sacrificial layer and patterned. The patterned structure has a pair of opposing sidewalls extending upwardly from the substrate. A pair of opposing corners are defined where the sidewalls join the substrate. The opposing corners are closer to one another than they would be if the sacrificial layer was absent and the imagable material was on the first layer during the patterning of the imagable material. The sacrificial layer is removed from the patterned structure.
In yet another aspect, the invention encompasses a structure comprising a first layer of silicon nitride over a substrate, and a second layer on the first layer. The second layer comprises silicon and is free of nitrogen. The structure further comprises a third layer consisting essentially of imagable material on the second layer.